Ikuto's flirting is always the best, because he doesn't beat around the bush and just gets straight to the point. He doesn't hesitate to flirt physically, either, as he demonstrated with biting Amu's ear, placing his hands on her hips multiple times, ruffling her hair, etc. The reason Ikuto's flirting is so effective is because he treats Amu like a child. He knows that she's stubborn and likes to hide behind her 'cool and spicy' facade. When he breaks that facade, Amu effectively gets flustered, yet she has a lot more fun than she does when she's bundling up her personality inside. His flirtations are almost similar to the skills of a guardian character, he gets Amu to become a different person, the one that she wants to be. Ikuto is essentially teaching her that she is still perfectly good, 'cool and spicy' or not. He doesn't give Amu much support, though, with all of his disappearing acts. Even when he is there, he still acts jealous when she talks with basically any other which makes this ship a bit unhealthy.

Summary: Though Ikuto is a bit controlling when he gets jealous, this ship is pretty cute altogether and really brings out the best in both Amu and Ikuto.

I got question went is Ikuto going to become more of main character ? because right now I am in Ep 8

I think he becomes more of a main character in the second season if i remember correctly. Havent watched in maybe 3 years. I should re-watch the series again:)

umm I think its the cutest:) Ikuto never goes beyond the limit since she is just a kid. But you can tell he really loves her, and even if Amu acts all like whatever to hide her true character, she enjoys being around him. ahh I wish there was a movie about them I'd be the happiest girl in the world.

what do you mean by Ikuto never goes beyond the limit ? I am really curious

i think that person meant that he never went to far with her as far as romantic interactions went.
SPOILERS:
He had said to her "Just grow up" or something along those lines, implying he wouldn't want to do anything with her since she was young.
In the manga (better than the anime imo) he also said something along the lines of "I'll wait for you"
There is also that time in both the anime and the manga where he leans in and just barely kisses her (in a teasing way), which gets Amu all flustered and 'angry'.

All in all, I think he was truly in love with her but knew she was a kid and didn't want to push it. He was kind of pervy, but he never did anything too bad haha